Rode around today to see if the surging would stop because I installed the DNA stage 1 airfilter.
Actually it got worse.
Next to that my Leovince X3 exhaust stopped backfiring.
(don't know what that means but I liked the backfiring

)
So I pulled my sparkplug to see that it was dry and black.
That would mean it is running to rich (i think).
But why do I have a problem with it now After installing the new airfilter.
To me it does not make sense.... but I ain't a mechanic.